1. Field of the Invention
The present invention relates in general to spring-loaded friction clutches and in particular to an improved self adjusting device for automatically compensating for wear in the friction surfaces of such clutches.
Automatic adjusting devices are well known in the art and are typically interposed in the lever system of a friction clutch so as to be operable to compensate for wear of the friction surfaces therein. While a number of such devices operate in a satisfactory manner to compensate for wear, numerous parts are often required to accomplish the desired result. Furthermore, the operating parts are frequently disposed outside the cover of the clutch, thereby subjecting them to possible damage. Those devices which position the operating parts within the cover usually require an excessive number of additional operating parts, resulting in a structure which is exceptionally difficult to service. Also, such devices are typically secured to the cover of the clutch by a mounting bracket which obstructs the view of the inner workings of the adjusting device, making visual confirmation of correct installation and function of the device impossible.
2. Description of the Prior Art
U.S. Pat. No. 3,752,286 to Sink discloses an automatic adjusting device for a spring-loaded friction clutch. The self adjusting device is incorporated in the lever system of the clutch between an actuating collar and an axially movable adjuster ring so as to be operable to advance the adjusting ring by very small increments as the friction surfaces of the clutch wear. The self adjusting device includes a flat mounting bracket which is bolted to the cover of the clutch. A pair of spaced apart ears extend inwardly from the flat mounting bracket so as to support the workings of the self adjuster device.
U.S. Pat. No. 2,241,223 to Spase et al. discloses an automatic wear take-up device for a friction clutch. The device includes a ratchet for coacting with an axially adjustable abutment of the clutch so as to shift the abutment axially. A pawl mechanism is operable by movement of a throw-out sleeve into or out of a position beyond its normal starting position. A closure plate mounted over an opening in the clutch cover can be removed to permit initial positioning of the device.
U.S. Pat. No. 4,099,604 to Higgerson discloses a friction clutch having an integral adjuster mechanism. The adjuster mechanism includes a bracket which is secured to one component of a pressure plate and a pair of lugs which support a cross shaft. A worm gear is supported for rotation with the shaft and is arranged to mesh with dog teeth of a second component of the pressure plate. A primary adjuster lever has two lugs which are pivotally secured about the cross shaft. A secondary adjuster lever is pivotally connected between the primary adjuster lever and a clutch release sleeve.
Other related devices are disclosed in U.S. Pat. No. 1,525,704 to Trumble, U.S. Pat. No. 1,865,772 to Lyman, U.S. Pat. No. 2,207,051 to Colman, U.S. Pat. No. 2,280,355 to Spase et al., U.S. Pat. No. 2,758,691 to Palm, U.S. Pat. No. 4,189,043 to Steinhagen, and U.S. Pat. No. 4,228,883 to Palmer.